FRAMEWORK MATERIALS

The main differences between the materials used for greenhouse frames is whether maintenance is necessary or not, whether you intend to heat during the winter months, how well the building might blend into your own garden environment, or whether the frame is strong enough to withstand the worst of the UK weather, especially now we are experiencing such extreme weather conditions these days.

ALUMINIUM
A number of manufactures offer greenhouses with aluminium frames. The price range is wide but so is the standard of quality and strength.

ADVICE
The general advantages of choosing a greenhouse with an aluminium frame is that there is no maintenance required. This is why the professional grower's main choice is aluminium as they simply want to get on with the business of profitable greenhouse growing and forget the structure and expensive maintenance. With the introduction about seven years ago of the green Polyester powder coating of aluminium greenhouse frames by most manufactures, even an aluminium greenhouse can now blend into most garden environments. I strongly advise you to consider a long established manufacturer such as Robinsons whose frame design and strength for the amateur grower comes from many years producing greenhouses for the professional grower.

TIMBER
The most popular type of timber used for greenhouses is cedar but softwood is also available. Timber frames very marginally conserve heat more than other frame materials used for greenhouses but remember all of them still have large areas of glass which will need insulating during winter months.

ADVICE
Softwood greenhouses are less expensive but beware, they have serious problems with warping and the need very frequent maintenance. Cedar has a natural oil content and manufacturers such as Alton also dip their greenhouse frames into a preservative before leaving the factory. Because of this, cedar needs less frequent maintenance than softwood. However don't lose sight of the fact that if you select a cedar greenhouse and wish to protect your investment, you would be wise to still paint with preservative at about 3 yearly intervals. This can be a chore or not, dependent on your view. I have personally replaced a number of rotten cedar greenhouses because despite the owners original good intentions they had not regularly maintained them.

STEEL
Steel is the forerunner to the present day aluminium extruded framework.  The original steel greenhouses meant putty had to be used to fix glass which is not ideal if glass breakage is experienced.  Steel frames however are used in tubular form to support Poly tunnels on which sheets of polythene are stretched.

ADVICE
Poly tunnels are not very practical or attractive for the amateur grower.  They were designed for and are mostly used by professional growers as less expensive cover for the production of vast quantities of bedding and other plants used in the short term.

PLASTIC
Two types are currently on the market.  One type is fully double glazed offered in the rectangular shape using a series of square white PVCu frames.  The other is a push fit tubular framed greenhouse made from a green resin compound.

ADVICE
The  first option is normally offered by double glazing companies which are usually extremely expensive but beware that over the years such companies have come and gone in the greenhouse industry.  The green tubular resin type greenhouse with clip together framework offered is very light and unfortunately only has the option of plastic glazing which could be a problem Neither of these frames are tried and tested in a growing environment. (see the section GLAZING OPTIONS) .